Star clusters are huge collections of densely packed stars which can not be navigated by ships.
Ships that try to navigate or even hyperjump through the star cluster itself will be instantly destroyed. If one ship tries to tow another ship into the star clusters, both ships will be stopped.
Ships may navigate through the radiation that the star clusters emit, but non-Robotic ships that move through, hyperjump across, or stay in the radiation will lose crew and colonists each turn equal to the strongest point of travel in the radiation. Ships that trigger a normal mine or get hit by a glory device while inside radiation will lose additional crew/colonists equal to the radiation at the point of impact due to the sudden hull breach. Ships that have a cloaking device can reduce their crew/colonist loss by 50% by activating the cloaking device.
Warp Chunnels are not factored into the calculations. They take place after all of the previous calculations are performed. Ships exiting radiation via a chunnel will still be penalized as normal (assuming no shielded starbase protecting the ships), but ships entering radiation from a non-radiated zone are safe on the turn they chunnel.
Ships that lose all of their crew to the radiation will become a ghost ship. This ship may be tow-captured by any dual-engine vessel with 20 or more crew.
- Main article: Radiation Shielding
Some ships are equipped with radiation shielding which protects the ship's crew/colonists from radiation.
Colonists and natives that are currently on planets are protected from the radiation due to the planet's atmosphere. In order for the same to be applied to ships, non-Robotic players must build a radiation shielded starbase (requiring 145 Du, 582 Tr, 380 Mo, and 1100 mc) on planets that are inside radiation. Robotic players continue to build normal starbases, since their crew/colonists are entirely immune to radiation.
These specialized starbases protect not only the starships of the owner, but also its allies. They can also hold 20 more fighters and 50 more defenses than normal starbases, and naturally gain 200 kT in combat mass as well. Only ships that remain at a planet containing such a starbase (even newly built starbases) benefit from its protection.
Ion storms that interact with the radiation gain strength, but will be instantly killed if they come into contact with a star cluster.